We have been studying the efficacy of local injections of botulinum toxin for the treatment of different types of focal dystonias. Botulinum toxin injected in small doses directly into muscle, binds to the neuromuscular junction and inactivates it for approximately three months. We have also been using botulinum toxin to study the physiology of focal dystonias. Studies of the utility of botulinum toxin are being carried out in writer's cramp (and its variants such as pianist's cramp) in open-label and double-blind rials. Treatment appears effective at least in the short-term. Longer follow-up on our patients is now being analyzed. In our subgroup of patients with musician's cramp, most of the patients eventually decide the treatment is insufficient for their needs. We are conducting a phase I trial of botulinum toxin type F to see if this will benefit patients who have developed antibodies to type A. In the first 16 patients, it appears to have similar efficacy and side effects to type A.